Display panel, electronic apparatus with the same, and method of manufacturing the same

ABSTRACT

There is provided a display panel that is capable of improving visibility outdoors and which can be easily manufactured. In a display panel in which at least one side thereof serves as a display surface, the display panel includes a first reflectance layer  3,  which is made of titanium, titanium nitride, or an alloy of titanium and tungsten and a second reflectance layer  4,  which is made of indium tin oxide, indium zinc oxide, or gallium zinc oxide, wherein the first and second low reflection layer  3  and  4  are deposited at positions corresponding to pixels on a substrate  1.

TECHNICAL FIELD

[0001] The present invention relates to a display panel and the like.More particularly, the present invention is directed to improve lowvisibility due to the reflection of light incident from the exterior.

BACKGROUND ART

[0002] Recently, display devices utilizing a liquid crystal display(LCD), an organic electroluminescent element (hereinafter, referred toas ‘an organic EL element’), and the like are employed in variouselectronics, such as a cellular phone, a personal computer, anelectronic organizer, a portable electronic game console, and the like.As such, users have many opportunities to look at a display screen ofthe electronic apparatus outdoors as well as looking at the screenindoors.

[0003] This case discusses in which light is incident on the displayscreen from the exterior. The incident light is reflected from thescreen back to viewers. However, more intense light is incident on thescreen and is reflected from the screen back to the viewers not indoors,but outdoors. As such, the contrast of the display device is reduced,thereby reducing the quality of the display image.

[0004] Herein, a case in which an organic EL element is employed willnow be considered. Since the organic EL elements, which areself-luminescent elements, have high visibility and response speed, thedisplay devices employing the organic EL elements are suitable todisplay moving pictures. However, existing organic EL elements do notsimultaneously realize high luminance and a long lifespan. As such, itis impossible to avoid a reduction in visibility due to the effect oflight incident from the exterior out of doors. Therefore, in order toimprove contrast, a display device has been disclosed in which anantireflection film composed of a laminated film of TiO₂ and SiO₂ isformed on the inner and outer surfaces of a cover for sealing thedisplay device (for example, see Japanese Unexamined Patent ApplicationPublication No. 2001-23072). Further, another display device has beendisclosed in which a circular polarizing plate is formed to a surface ofthe cover to suppress the reflection of light incident from the exterior(for example, see Japanese Unexamined Patent Application Publication No.8-321381). In addition, a structure has been disclosed in which TaO_(x)(tantalum oxide) deposited under a reactive atmosphere or by CVD is usedas an absorption layer in order to improve contrast (for example,. seeJapanese Patent No. 2901370). Furthermore, an organic EL element, inwhich an charge injecting layer having light absorption and diffusionproperties (for example, see Japanese Patent No. 2931229) is provided, adisplay panel with a black absorbent formed on the bottom thereof (forexample, see U.S. Pat. No. 5,986,401, and an organic EL element, inwhich a black multi-layered film is used for an electrode (for example,see Japanese Unexamined Patent Application Publication No. 2003-17274)have been disclosed.

[0005] In these conventional display devices, since an expensive member,such as a circular polarizing plate, must be provided to a displaydevice, more expense and effort are required, thereby increasing costs.In addition, since a filter, such as a circular polarizing plate, isprovided, even though the organic EL element emits light, the light isnot emitted externally, thereby lowering actual brightness and thusreducing visibility.

[0006] A display device has been disclosed in which a triple-layeredfilm of a reflective aluminum film, a silicon oxide/aluminum film, andan aluminum transflective film is used to suppress reflectance. However,in this case, it is not easy to manufacture the display device due toits complicated structure. Further, when the triple-layered film is usedas an anode, a separate conductive film having a high work function hasto be deposited.

[0007] The present invention is designed to solve the aforementionedproblems, and it is an object of the present invention to provide adisplay panel capable of being easily manufactured and improvingvisibility outdoors as well.

DISCLOSURE OF INVENTION

[0008] A display panel according to the present invention comprises: afirst low reflection layer made of titanium and deposited on aelectrode; a second low reflection layer made of indium tin oxide anddeposited on the first low reflection layer; and light-emitting elementsdeposited on the second low reflection layer.

[0009] According to the present invention, the display panel includesthe first low reflection layer of titanium and the second low reflectionlayer of indium tin oxide formed on the substrate, thereby considerablyreducing the reflection of light incident from the exterior by theinteraction of the respective layers including the light-emittingelements and their interfaces. As such, visibility can be improvedoutdoors. Further, a basic structure for reducing reflection may beconstructed by two layers, so that the display panel is easilymanufactured.

[0010] In addition, a display panel according to the present inventioncomprises: a substrate provided with control elements for controllingthe supply of electric charge to pixels; a first low reflection layermade of titanium and deposited at positions corresponding to the pixelson the substrate; a second low reflection layer made of indium tin oxideand deposited on the first low reflection layer; and light-emittingelements, functioning as the pixels, deposited on the second lowreflection layer and emitting light based on the supplied electriccharge.

[0011] According to the present invention, since the display panelincludes the first low reflection layer of titanium and the second lowreflection layer of indium tin oxide formed on the substrate providedwith control elements, such as TFTs, thereby considerably reducing thereflection of light incident from the exterior by the interactionbetween the respective layers including the light-emitting elements andtheir interfaces. Accordingly, a degree of freedom relating to thearrangement of the control elements and wiring lines on the substratecan increase on the side of the substrate rather than on the first lowreflection layer having a low contribution to the reflection.

[0012] According to the present invention, there is provided a displaypanel comprising: a substrate provided with control elements forcontrolling the supply- of electric charge to pixels for displaycontrol; a first low reflection layer of titanium deposited at positionscorresponding to the pixels on the substrate; a second low reflectionlayer of indium tin oxide deposited on the first low reflection layer;light-emitting elements deposited on the second low reflection layer andemitting light based on the electric charge supplied under the controlof the control elements; a conductive film deposited on thelight-emitting elements and supplying to the light-emitting elementselectric charge having a polarity opposite to the electric chargesupplied from the second low reflection layer; and a sealing memberprovided on the conductive film as a display surface and facing thesubstrate.

[0013] According to the present invention, in the display panel, thefirst low reflection layer made of titanium, the second low reflectionlayer made of indium tin oxide, the light-emitting elements, and theconductive film are deposited on the substrate provided with the controlelements, such as TFTs, and then the sealing member is provided thereon.Accordingly, since indium tin oxide is also deposited on the bondingportions between the substrate and the sealing member when the secondlow reflection layer is deposited, the adhesion between the substrateand the sealing member can be improved due to the roughness effect ofindium tin oxide in the case of using the adhesive. Therefore, it ispossible to securely prevent the permeation of moisture and oxygen intothe display panel.

[0014] Furthermore, in the display panel according to the presentinvention, the second low reflection layer is deposited with a thicknessof 60 nm to 100 nm.

[0015] According to the present invention, in a case where the secondlow reflection layer has a thickness of 60 nm, the minimum reflectanceof light is obtained in the vicinity of a wavelength of 70 nm. Further,in a case where the second low reflection layer has a thickness of 100nm, the minimum reflectance of light is obtained in the vicinity of awavelength of 100 nm. In the outdoors, in a case where the second lowreflection layer has a thickness of 60 nm to 70 nm, good visibility canbe obtained.

[0016] In the display panel according to the present invention, thesecond low reflection layer is made of indium zinc oxide, gallium zincoxide, or indium cerium oxide instead of indium tin oxide.

[0017] According to the present invention, the second low reflectionlayer is made of indium zinc oxide, or gallium zinc oxide, which is aconductive material similarly to the indium tin oxide. Contrary to ITO,even though these materials are deposited in an atmosphere containing nooxygen, they can have high conductivity. Therefore, dependency upon anoxygen concentration in the deposition is small, and highreproducibility can be obtained in its manufacture. Also, since thematerials have a high stability, the deterioration thereof is small astime passed. In addition, since indium cerium oxide has a work functionsuitable for injecting electric charge into a light-emitting material,high injection efficiency of electric charge can be obtained. Further,since indium zinc oxide has a work function suitable for injectingelectric charge into a light-emitting material, high injectionefficiency of electric charge can be obtained. Furthermore, since theinternal stress of the film is low, the adhesion between the substrate,the light emitting layer, the electric charge injecting layer, and theelectric charge transporting layer is high, and thus the lifespan of thelight-emitting device can be lengthened.

[0018] In addition, in the display panel according to the presentinvention, the conductive film is made of indium cerium oxide. Eventhough indium cerium oxide is deposited in an atmosphere containing nooxygen, it can have high conductivity. Therefore, the influence thereofon the light-emitting layer, the electric charge injecting layer, andthe electric charge transporting layer at the time of deposition can besuppressed, thereby prolong the lifespan of the light-emitting elements.

[0019] Furthermore, in the display panel according to the presentinvention, the second low reflection layer is deposited such that thearithmetic mean roughness Ra of surface thereof measured by astylus-type step-difference measuring apparatus is in the range of 4 nmto 11 nm.

[0020] According to the present invention, the surface of the second lowreflection layer is crystallized, and the second low reflection layer isdeposited such that the arithmetic mean roughness Ra of surface thereofis in the range of 4 nm to 11 nm. As a result, the surface is not madesmooth. Since the surface of the second low reflection layer is notsmooth, reflectance can be more reduced. The reason is that thethickness of the second low reflection layer is locally not uniform andthe interaction among the first low reflection layer, the respectivelayers including the light-emitting element, and their layers isachieved with respect to the light of various wavelengths. In this case,if the surface is too rough, a short circuit occurs, and if the surfaceis too smooth, a sufficient effect is not obtained. Therefore, Raincluding the substrate is preferably within the range of 10 nm to 100nm.

[0021] In the display panel according to the present invention, thefirst low reflection layer is made of titanium nitride instead oftitanium.

[0022] According to the present invention, since titanium nitride havinga high absorbing effect in a visible ray is used, the reflectance oflight incident from the exterior can be more reduced.

[0023] Further, in the display panel according to the present invention,the first low reflection layer is made of an alloy of titanium andtungsten instead of titanium.

[0024] According to the present invention, since the alloy of titaniumand tungsten having a high absorbing effect in a visible ray is used,the reflectance of light incident from the exterior can be more reduced.

[0025] Furthermore, in the display panel according to the presentinvention, a titanium oxide layer is provided between the first andsecond low reflection layers.

[0026] According to the present invention, a titanium oxide layerabsorbing light of a predetermined wavelength is provided between thefirst and second low reflection layers. Accordingly, the reflectancewith respect to light of a predetermined wavelength can be reduced.

[0027] Moreover, in the display panel according to the presentinvention, the first low reflection layer is deposited with a thicknessof 30 nm to 400 nm.

[0028] According to the present invention, if the thickness of the firstlow reflection layer is 30 nm or less, reflectance is high. If thethickness is 400 nm or more, an internal stress is easily produced, andthere are possibilities that the substrate bends, the film peels off, orthe elements are broken down. Further, it is difficult to manufacturethe substrate.

[0029] In addition, in the display panel according to the presentinvention, the thickness of ITO for forming the second low reflectionlayer is within the range of 62 nm to 82 nm, the thickness of ITO forforming the conductive film is within the range of 135 nm to 155 nm, alight-emitting polymer for forming the light-emitting layer constitutingthe light-emitting element is deposited with a thickness of 70 nm to 90nm, or 150 nm to 170 nm, and the hole injecting and transporting layeris deposited with a thickness of 80 nm to 100 nm, or 170 nm to 190 nm.

[0030] According to the present invention, reflectance can be reducedwithout degrading the light-emitting characteristic of thelight-emitting element. Therefore, in a case where light is incidentfrom the exterior, contrast can increase, and visibility can beimproved.

[0031] Further, in the display panel according to the present invention,a planarizing film is provided between the substrate and the first lowreflection layer.

[0032] According to the present invention, by providing the planarizingfilm, the influence of the step difference due to the driving device andwiring lines can be reduced, and the reproducibility of characteristicat the time of depositing the first and second low reflection layers canbe improved. Further, a pattern can be easily formed. In addition, sincethe step difference on the substrate is reduced, a sealing performanceis improved, thereby reducing the characteristic discordance between thepixels due to a short circuit, etc.

[0033] Furthermore, in the display panel according to the presentinvention, a chromium layer is further deposited on the second lowreflection layer.

[0034] According to the present invention, the chromium layer is furtherdeposited on the second low reflection layer, and the low reflectionlayer also functions as a hole injecting layer to improve the injectionefficiency of hole.

[0035] Moreover, in the display panel according to the presentinvention, in a step of forming the control elements and the wiringlines and a step of forming the first low reflection layer or the secondlow reflection layer, some of or all of the steps are commonly used.

[0036] According to the present invention, the formation of othercircuits including the control elements and the deposition of the firstor second low reflection layer may be performed with the same materialby a series of process or a mixed process, and the equipment may beshared. As such, it is possible to effectively manufacture the panel andto cope with the miniaturization and high integration of element.Further, even if a display panel with a high function and high precisionis manufactured, an increase in cost can be suppressed.

[0037] In addition, the display panel according to the present inventioncomprises a black layer having a function of reducing a step differenceat a lower portion and light-emitting elements provided on the blacklayer.

[0038] According to the present invention, the black layer is depositedon the substrate by, for example, a spin coating method. Light incidentfrom the exterior is absorbed by the black layer to suppress thereflection of light and thus to reduce reflectance. Further, since theblack layer is deposited by the spin coating method, the influence of astep difference due to the control elements at the lower portion, wiringlines, etc., can be reduced. As such, even if an organicelectroluminescent device is formed of the black layer as in an organicEL display panel, it is possible to improve the uniformity of thethickness of the light-emitting layer, thereby improving the uniformityin the light-emitting surface.

[0039] Furthermore, the display panel according to the present inventioncomprises a conductive black layer formed on a substrate andlight-emitting elements provided on the black layer and emitting lighton the basis of the supplied electric charge.

[0040] According to the present invention, the conductive black layermade of a material in which a black pigment is added to a conductiveresin or a material in which carbon black is dispersed in the conductiveresin is deposited at positions corresponding to the pixels.Accordingly, the black layer absorbs light incident from the exteriorand also serves as an electrode for supplying electric charge.Therefore, it is not necessary to form the electrode again.

[0041] Moreover, in the display panel according to the presentinvention, the black layer is made of an allotrope of carbon.

[0042] According to the present invention, the black layer is made of anallotrope of carbon, such as graphite, diamond like carbon, amorphouscarbon, etc. Accordingly, the black layer absorbs light incident fromthe exterior and also serves as an electrode for supplying electriccharge. Therefore, it is not necessary to form the electrode again.Further, since the black layer has high conductivity, the deteriorationof the light-emitting characteristics of the light-emitting element canbe suppressed.

[0043] In addition, in the display panel according to the presentinvention, control elements for controlling the supply of electriccharge to the light-emitting element are formed on the substrate, andPeltier elements are formed at portions other than a display portion onthe substrate.

[0044] According to the present invention, in order to radiate the heatgenerated by the absorbed light out of the panel, the Peltier elementsand the control elements are formed through a common process. Apolycrystal, crystallite or amorphous silicon layer, which is an activeregion of the control element, may be used as a part of the Peltierelement. Accordingly, for example, in the case of the display deviceusing an organic EL element, by preventing an increase in temperature ofthe organic EL element, it is possible to lengthen the lifespan of thelight-emitting element. In addition, the Peltier elements are integrallyformed on the substrate, and a reduction in cost and the miniaturizationthereof can be achieved.

[0045] Furthermore, an electronic apparatus according to the presentinvention comprises a display panel as described above to performdisplay.

[0046] According to the present invention, the display panel of thepresent invention is used for display portions of electronicapparatuses, such as a cellular phone and a digital camera. As such, thevisibility of the electronic apparatuses can be improved by suppressingthe reflection of light incident from the exterior. Accordingly, whenthe electronic apparatuses are used outdoors, a marvelous effect can beobtained.

[0047] Moreover, according to the present invention, there is provided amethod of manufacturing a display panel having a plurality of pixels,the method comprising the steps of: forming a first low reflection layerof titanium at positions corresponding to pixels on a substrate; andforming a second low reflection layer of indium tin oxide on the firstlow reflection layer.

[0048] According to the present invention, by depositing the first lowreflection layer of titanium and the second low reflection layer ofindium tin oxide on the electrode and by the interaction between therespective layers including the light-emitting elements and theirinterfaces, it is possible to considerably reduce the reflection oflight incident from the exterior. Accordingly, visibility can beimproved even if the display panel is used outdoors. Further, since abasic structure for reducing reflection is constructed by only twolayers, it is possible to easily manufacture the display device.

[0049] In the method of manufacturing the display panel according to thepresent invention, the first low reflection layer and the second lowreflection layer are patterned so as to remain only at the positionscorresponding to the pixels after the first and second low reflectionlayer are deposited by either a sputtering method or a depositionmethod.

[0050] According to the present invention, after the first lowreflection layer or the second low reflection layer is deposited by thesputtering method or the deposition method and is formed in apredetermined pattern by the resist, the layer is etched by a wetetching or a dry etching to form the first and second low reflectionlayers at the positions corresponding to the respective pixels. Withsuch a manufacturing method, the pattern can be formed with highprecision, and a display panel with high performance and high precisioncan be easily achieved.

[0051] Further, in the method of manufacturing the display panelaccording to the present invention, the first low reflection layer andthe second low reflection layer are deposited by either a sputteringmethod or a deposition method so as to remain only at the positionscorresponding to the pixels after masking is previously performed at thepositions corresponding to the pixels.

[0052] According to the present invention, in a state where a maskhaving openings formed at positions where the first and second lowreflection layers are deposited adheres closely to the substrate, thefirst and second low reflection layers are formed at the desiredpositions by a sputtering method or a deposition method. In this manner,an etching process is not required, and the layers can be formed withoutdamaging a base layer, the control elements, the wiring lines, and thelike.

[0053] Moreover, in the method of manufacturing the display panelaccording to the present invention, the method further comprises thesteps of: forming light-emitting elements at the positions correspondingto the pixels after forming the second low reflection layer; forming, onthe light-emitting elements, a conductive film for supplying to thelight-emitting elements electric charge having a polarity opposite tothe electric charge supplied from the second low reflection layer; andperforming sealing using a transparent member to be a display surface.

[0054] According to the present invention, the light-emitting elements,such as organic EL elements, the conductive film, and the sealing memberare formed on the first low reflection layer. Accordingly, since indiumtin oxide, which is to be the second low reflection layer, is depositedat bonding portions between the substrate and the sealing member at thetime of depositing the second low reflection layer, adhesion between thesubstrate and the sealing member can be increased by the roughnesseffect of the indium tin oxide, and thus it is possible to securelyprevent the permeation of moisture and oxygen.

[0055] According to the present invention, there is provided a method ofmanufacturing a display panel, the method comprising the steps of:forming control elements for carrying out display control on pixels on asurface opposite to a display surface of a substrate; applying aphotosensitive resin containing a black pigment on thecontrol-element-forming surface of the substrate to form a black layer;and forming through-holes or grooves for supplying electric charge atpositions corresponding to the pixels using the black layer.

[0056] According to the present invention, the control elements areformed on silicon deposited on the substrate, the photosensitive resincontaining the black pigment is applied on the control-element-formingsurface of the substrate by, for example, a spin coating method to forma black layer, and the through-holes or grooves are formed on the blacklayer based on the positions of the pixels. Accordingly, light incidentfrom the exterior is absorbed by the black layer to suppress thereflection of light and thus to reduce reflectance. Further, since theblack layer is deposited by the spin coating method, the influence of astep difference due to the control elements at a lower portion, thewiring lines, and the like can be reduced. Therefore, even if organiclight-emitting elements are formed of the black layer as in an organicEL display panel, the uniformity of the layer thickness of thelight-emitting layer can be improved, and thus light can be uniformlyemitted. Further, an electrode for controlling the supply of electriccharge using the control element is directly connected to thelight-emitting element through the through-hole or groove.

[0057] A method of manufacturing a display panel according to thepresent invention comprises the steps of: forming control elements forcarrying out display control on pixels on a surface opposite to adisplay surface of a substrate; and forming a conductive black layer atpositions corresponding to the pixels on the control-element-formingsurface of the substrate.

[0058] According to the present invention, the conductive black layermade of, for example a material in which a black pigment is added into aconductive resin or a material in which carbon black is dispersed in theconductive resin is deposited at the positions corresponding to thepixels. Accordingly, the black layer absorbs light incident from theexterior and also serves as an electrode for supplying electric charge.Therefore, it is not necessary to form the electrode again.

[0059] In the method of manufacturing the display panel according to thepresent invention, since active regions of the control elements are madeof silicon, Peltier elements are also formed at portions other than adisplay portion on the substrate when the control elements are formed.

[0060] According to the present invention, in order to radiate the heatgenerated by the absorbed light out of the panel, the Peltier elementsand the control elements are formed through a common process. Apolycrystal, crystallite or amorphous silicon layer, which is an activeregion of the control element, may be used as a part of the Peltierelement. Accordingly, in the case of the display device using, forexample, an organic EL element, an increase in temperature of theorganic EL element is prevented, and thus the lifespan of the organic ELelement can be lengthened.

[0061] In the method of manufacturing the display panel according to thepresent invention, in the step of forming the black layer, the blacklayer is formed of graphite deposited by a vacuum deposition method or asputtering method.

[0062] According to the present invention, the black layer of graphiteis deposited by the vacuum deposition method or the sputtering method.Accordingly, the black layer absorbs light incident from the exteriorand also functions as an electrode for supplying electric charge.Therefore, it is not necessary to form the electrode again. Further,since the black layer has high conductivity, the deterioration of thelight-emitting characteristic of the light-emitting element can besuppressed.

[0063] Furthermore, in the method of manufacturing the display panelaccording to the present invention, in the step of forming the blacklayer, the black layer is formed of diamond like carbon deposited by achemical vapor deposition method.

[0064] According to the present invention, the black layer of diamondlike carbon is deposited by the chemical vapor deposition method.Accordingly, the black layer absorbs light incident from the exteriorand also functions as an electrode for supplying electric charge.Therefore, it is not necessary to form the electrode again. Further,since the black layer has high conductivity, the deterioration of thelight-emitting characteristic of the light-emitting element can besuppressed. Diamond like carbon is hard so that a scar is hardly formedon diamond like carbon at handling. Thus, the reliability is improved,and the yield increases.

[0065] In addition, the method of manufacturing the display panelaccording to the present invention further comprises the steps of:forming light-emitting elements at the positions corresponding to thepixels after forming the black layer; forming, on the light-emittingelements, a conductive film for supplying to the light-emitting elementselectric charge having a polarity opposite to the electric chargesupplied from the black layer; and performing sealing using a sealingmember.

[0066] According the present invention, the light-emitting elements,such as organic EL elements, the conductive film, and the sealing memberare formed on the black layer. Accordingly, since the sealing memberadheres to the substrate with good adhesion by a concavo-convex surfaceof the black layer, the reliability is improved, and the reflection iseffectively suppressed. Further, the visibility of the display panel canbe improved outdoors.

[0067] Further, in the method of manufacturing the display panelaccording to the present invention, in the step of forming thelight-emitting elements, after banks are formed to store a solution of apolymer compound for forming the light-emitting elements in regionswhere the pixels are formed, the solution is discharged at positionswhere the pixels are formed by a liquid drop discharging method.

[0068] According to the present invention, when the liquid dropdischarging method (ink jet method) is used to form the light-emittingelements, the partition is formed to store a solution in regions wherethe pixels are formed, and then a solution of a polymer compound forforming the light-emitting elements is discharged and deposited, therebyforming the light-emitting elements. Accordingly, the light-emittingelements can be easily manufactured by the liquid drop dischargingmethod without wasting the light-emitting-element material. These banksare also effectively used for forming the light-emitting elements using,for example, a vacuum deposition method.

BRIEF DESCRIPTION OF THE DRAWINGS

[0069]FIG. 1 is a cross-sectional view of a part of a display panelaccording to a first embodiment.

[0070]FIG. 2 is a plane view showing one pixel constituting the displaypanel.

[0071]FIG. 3 is a graph depicting the relationship among a filmthickness of Ti, which is a first low reflection layer 3, pressure insputtering, and reflectance.

[0072]FIG. 4 is a graph depicting the relationship among a filmthickness of Ti, which is the first low reflection layer 3, pressure insputtering, and maximum reflectance.

[0073]FIG. 5 is a graph depicting the relationship between the layerthickness of a second low reflection layer 4 and reflectance.

[0074]FIG. 6 is a graph depicting the relationship between reflectanceand a light incident and emitting angle for every wavelength when thefirst low reflection layer 3 and the second low reflection layer 4 aredeposited.

[0075]FIG. 7 is a graph depicting the relationship between reflectanceand a light incident and emitting angle for every wavelength when thefirst low reflection layer 3 of Ti and the second low reflection layer 4of ICO are deposited.

[0076]FIG. 8 is a cross-sectional view of a part of a display panelaccording to a second embodiment of the present invention.

[0077]FIG. 9 is a view of a patterned black layer 11.

[0078]FIG. 10 is a graph depicting the relationship between reflectanceand a light incident and emitting angle of the black layer 11.

[0079]FIG. 11 is a cross-sectional view of a part of a display panelaccording to a third embodiment of the present invention.

[0080]FIG. 12 is a graph depicting the relationship between reflectanceand a light incident and emitting angle of a black layer 11A.

[0081]FIG. 13 is a view depicting a display panel provided with aPeltier element.

[0082]FIG. 14 is a view depicting a sealing method according to a sixthembodiment of the present invention.

[0083]FIG. 15 is a view depicting an electronic apparatus according to aninth embodiment of the present invention.

REFERENCE NUMERALS

[0084]1: SUBSTRATE

[0085]2: ELECTRODE

[0086]3: FIRST LOW REFLECTION LAYER

[0087]4: SECOND LOW REFLECTION LAYER

[0088]5: EL LAYER

[0089]5A: HOLE INJECTING AND TRANSPORTING LAYER

[0090]5B: LIGHT-EMITTING LAYER

[0091]6: CONDUCTIVE FILM

[0092]7: BANK

[0093]8: SEALING FILM

[0094]8A: TRANSPARENT SUBSTRATE

[0095]11, 11A: BLACK LAYER

[0096]12: ADHESIVE

[0097]20: FIRST TFT

[0098]21: GATE ELECTRODE

[0099]22: DRAIN ELECTRODE

[0100]30: SECOND TFT

[0101]31: GATE ELECTRODE

[0102]36: EXTENDED PORTION OF GATE ELECTRODE 31

[0103]37: GATE INSULATING FILM

[0104]39: INSULATING PORTION OF COMMON ELECTRODE com

[0105]51: INTERLAYER INSULATING FILM

[0106]52: PLANARIZING INSULATING FILM

[0107]61: INSULATING PASSIVATION FILM

DESCRIPTION OF THE EMBODIMENTS First Embodiment

[0108]FIG. 1 is a cross-sectional view showing a part of the displaypanel according to a first embodiment of the present invention. In FIG.1, reference numeral 1 indicates a substrate. In this embodiment, thesubstrate 1 is provided with thin film transistors (hereinafter,referred to as TFTs) serving as control elements (driving elements)(only a second TFT 30 to be described later is shown in FIG. 1).

[0109]FIG. 2 is a plane view showing one pixel constituting a displaypanel. FIG. 2 shows elements formed mostly between a second lowreflection layer 4 (first low reflection layer 3) and the substrate. Agate electrode of a first TFT 20 is supplied with scanning signals via ascanning line ‘gate’. A storage capacitor ‘cap’ is adapted to hold imagesignals supplied from a data line ‘sig’ via the first TFT 20. A gateelectrode 31 of a second TFT 30 is supplied with the image signal heldby the storage capacitor ‘cap’.

[0110] The first TFT 20 and the second TFT 30 are formed of an isolatedsemiconductor film. A gate electrode 21 of the first TFT 20 isconstructed as a part of the scan line ‘gate’ and is supplied with thescan signal. One side of the source and drain regions of the first TFT20 is electrically connected to the data line ‘sig’ via a through-holein an interlayer insulating film 51, and the other side of the sourceand drain regions is electrically connected to a drain electrode 22. Thedrain electrode 22 is electrically connected to the gate electrode 31 ofthe second TFT 30 via the through-hole of the interlayer insulating film51. One side of the source and drain regions of the second TFT 30 iselectrically connected to an electrode 2 simultaneously formed with thedata line ‘sig’ via the through-hole in the interlayer insulating film51. The electrode 2 is electrically connected to the first lowreflection layer 3, the second low reflection layer 4, and an EL layer 5via the through-hole in a further planarizing insulating film 52.

[0111] The other side of the source and drain regions of the second TFT30 is electrically connected to a common feeding line ‘com’ via thethrough-hole in the interlayer insulating film 51. An extended portion39 of the common feeding line ‘com’ is opposite to an extended portion36 of the gate electrode 31 of the second TFT 30 with the interlayerinsulating film 51 formed therebetween, as a dielectric film, and thusforms the storage capacitor ‘cap’. Further, instead of the abovestructure in which the storage capacitor ‘cap’ is formed between thecommon feeding lines ‘com’, the storage capacitor may be formed betweenthe scanning line ‘gate’ and a capacitive line formed parallel to thescanning line ‘gate’. Also, the storage capacitor ‘cap’ may be formed ofthe drain region of the first TFT 20 and the gate electrode 31 of thesecond TFT 30. In this embodiment, TFTs (the first TFT 20 and the secondTFT 30) are utilized as elements for controlling the luminescence of therespective pixels. However, the present invention is not limitedthereto, and other control elements may be utilized. In addition, inthis embodiment, the substrate 1 is composed of alkali glass.

[0112] Reference numeral 2 indicates an electrode for injecting(supplying) holes or electrons (electric charges) into the EL layer 5.The electrode 2 is made of, for example, aluminum (Al), magnesium (Mg),and the like. However, the material is not limited thereto, and, forexample, transparent ITO (indium tin oxide), which is an indium oxidefilm doped with tin oxide as impurity, may be used. In addition, insteadof ITO, for example, IZO (indium zinc oxide), GZO (gallium zinc oxide),and ICO (InCeO; indium cerium oxide) may be utilized. Further, in thisembodiment, the electrode 2 is used as an anode, while a conductive film6, which will be described later, is used as a cathode.

[0113] Reference numeral 3 indicates a first low reflection layer. Inthis embodiment, pure titanium (Ti) is used as a material of the firstlow reflection layer 3. However, titanium nitride (TiN) and an alloy oftitanium and tungsten (TiW) may be used. Furthermore, a layer oftitanium oxide (comprise TiO_(x), Ti₂O₃, and Ti₂O₅) may be providedbetween the first low reflection layer and the second low reflectionlayer. The reason is because a local color of TiO_(x) can reducereflectance within a specific range. In this embodiment, as the secondlow reflection layer 4, ITO (or, IZO, GZO, and ICO) is utilized. In thisembodiment, the first low reflection layer 3 and the second lowreflection layer 4 also serve as an electrode of a light-emittingelement. Further, the-first low reflection layer 3 made of Ti may beused as the electrode 2.

[0114] Reference numeral 5 indicates an EL layer constituting theorganic EL element (light-emitting element). In this embodiment, the ELlayer 5 comprises the hole injecting (transporting) layer 5A composedof, for example, thiophene-based conductive polymer, and alight-emitting layer 5B of light-emitting polymer (LEP). Alternatively,the EL layer 5 may have a structure in which the hole (electron)injecting layer is separated from a hole transporting layer, athree-layered structure of an electron injecting layer, a hole injectinglayer, and a light-emitting layer, and a structure in which EL layers 5different in structure are deposited. Furthermore, the second lowreflection layer 4 composed of ITO, etc., may also function as the holeinjecting layer, and the thiophene-based conductive polymer may functionthe hole transport layer. Reference numeral 6 indicates a conductivefilm, as the other electrode, for injecting (supplying) holes orelectrons into the EL layer 5. In this embodiment, the conductive film 6may be composed of ITO (or IZO, GZO, and ICO), which is transparent in avisible ray range, similarly to the second low reflection layer 4. Inaddition, since ITO has a relatively high value of work function, inthis case, an interface layer of the electron injecting layer of the ELlayer 5 is added with, for example, BCP (biphasic calcium phosphate) andcesium (Cs) or is deposited with magnesium (Mg) and silver (Ag) toeasily inject electrons. Further, the light-emitting control (controlfor supplying electric charges) for the EL layer 5 of the respectivepixels of the display panel is achieved by TFTs (first TFT 20 and secondTFT 30) provided to the respective pixels via the electrode 2corresponding to the EL layer 5 of the respective pixels. Therefore, itis not necessary to separately provide the conductive film 6 on the ELlayer 5 of each pixel. Also, since electrons are easily injected intoICO from the viewpoint of the work function, and ICO has a lower sheetresistance than ITO, it is possible to supply electric charge to theentire display panel at a low voltage.

[0115] Reference numeral 7 indicates a bank (partition) for storing asolution at a region forming the EL layer 5 in a case where the EL layer5 of a polymer organic compound is formed by a liquid drop dischargingmethod used for, for example, an inkjet printer. The bank 7 is composedof a photosensitive organic material, such as polyimide, acryl and thelike, which is patterned using a photolithography method. Referencenumeral 8 indicates a sealing film that is a sealing member. The sealingfilm 8 is made of, for example, silicon nitride (SiN), ITO and the like.If the organic EL element is exposed to moisture, oxygen and so forth,luminescent lifetime is shortened. Thus, the sealing film 8 is providedto prevent moisture, oxygen, etc., from permeating to the EL layer 5.

[0116] In the display panel of the present embodiment, a dual lowreflection layer comprising the first low reflection layer 3 and thesecond low reflection layer 4 are provided in the vicinity of the anodethat is a layer positioned lower than the EL layer 5 to reduce thereflection by the interaction of the respective layers and theirinterfaces. As such, a display panel with a simple structure and capableof suppressing the reflection of light incident from the exterior and ofimproving visibility outdoors can be obtained.

[0117] Next, a method of manufacturing the display panel according tothis embodiment will be described. First, a semiconductor film made ofamorphous silicon having a thickness of about 30 to 70 nm is formed onthe substrate 1, for example, by a plasma CVD method. Then, thesemiconductor film of the amorphous silicon film is changed into apolycrystal silicon film by performing a crystallizing process, such asa solid phase epitaxy and a laser annealing. Next, the semiconductorfilm is patterned to form an isolated film, and a gate insulating film37 composed of a silicon oxide film or a silicon nitride film having athickness of about 60 to 150 nm is formed on a surface of thesemiconductor film.

[0118] Next, the conductive film made of, for example, titanium (Ti) andtungsten (W) is formed by a sputtering method and is then patterned toform gate electrodes 21 and 31 and the extended portion 36 of the gateelectrode 31. Further, the scanning line ‘gate’ is formed.

[0119] In this state, phosphorus ions of high concentration are doped,and the source and drain region is self-aligned with respect to the gateelectrode. Next, after the interlayer insulating film 51 is formed, therespective through-holes are formed. Then, the data line ‘sig’, thedrain electrode 22, the common feeding line ‘com’, the extended portion39 of the common feeding line ‘com’, and the electrode 2 (a portionherein) are formed. As a result, the first TFT 20, the second TFT 30,and the storage capacitor ‘cap’ are formed. Although it is not shownherein, a driving circuit and other circuits may be simultaneouslyformed on portions other than the display portion.

[0120] Next, in order to reduce the effect due to a step generated bythe formation of the control element, the planarizing insulating film 52is formed before the first low reflection layer 3 is formed. Theplanarizing insulating film 52 is formed by applying, for example,polyimide or acryl using a spin coating method. A through-hole is formedat a portion corresponding to the connecting portion between theelectrode 2 of the planarizing interlayer insulating film 52 and thesecond TFT 30. Next, after a conductive layer, which is the electrode 2,is deposited on the entire surface and is patterned, the first lowreflection layer 3 is connected to the source and drain region of thesecond TFT 30. In addition, although the planarizing insulating film 52is formed by the spin coating method in this embodiment, a method may beused in which, after a silicon oxide film or a silicon nitride film isformed by a CVD method, acryl, resist and the like are deposited by aspin coating method, and an etchback is performed thereon to flatten thesurface.

[0121]FIG. 3 is a graph depicting the relationship among the thicknessof titanium, which is used for the first low reflection layer 3,pressure at the time of sputtering, and reflectance. FIG. 3 depictsreflectance at an incident and emitting angle of 20°. Also, FIG. 4 is agraph depicting the relationship among the film thickness of Ti, whichis used for the first low reflection layer 3, pressure at the time ofsputtering, and maximum reflectance. In the present embodiment, the term‘maximum reflectance’ means the maximum value of the reflectance in avisible ray range (400 nm to 700 nm). In general, it may be consideredthat, if the maximum reflectance is low, reflectance is low over thewhole visible ray range. As can be seen from FIGS. 3 and 4, thereflectance also depends upon the thickness of Ti (first low reflectionlayer 3) and pressure at the time of sputtering.

[0122] After the control element and the electrode 2 are formed on thesubstrate 1, a thin Ti layer, which is the first low reflection layer 3,is deposited by a sputtering method using a DC magnetron. In thisembodiment, for example, the deposition is performed in an argonatmosphere under the conditions where the pressure is 0.3 Pa andelectric power is 500 W. Although the sputtering method using the DCmagnetron is utilized in this embodiment, the deposition method is notlimited to the sputtering method, and an ion beam deposition method maybe utilized. Herein, the first low reflection layer 3 is deposited tohave a thickness of 30 nm to 400 nm. If the film thickness is 30 nm orless, reflectance is high. If the film thickness is 400 nm or more,internal stress is easily generated. As a result, there arepossibilities that the substrate bends, the film peels off, and thebreakdown of elements occurs. Further, it is difficult to process thesubstrate.

[0123]FIG. 5 is a graph depicting the relationship between the layerthickness of the second low reflection layer 4 and reflectance. FIG. 5depicts two cases: the layer thickness of the second low reflectionlayer 4 is 116 nm; and the layer thickness of the second low reflectionlayer 4 is 78 nm. A thin film of ITO, which is the second low reflectionlayer 4, is deposited by the sputtering method using the DC magnetron,similarly to the first low reflection layer 3. In this embodiment, thedeposition is performed under the conditions where the sputteringpressure is 0.3 Pa and electric power is 100 W. Further, the sputteringis performed under the conditions where a flow rate of argon gas tooxygen gas is 100:1 and a target of 4 inches is used. Herein, thewavelength dependency of the reflectance varies according to a variationin layer thickness as shown in FIG. 5. If the layer thickness of thesecond low reflection layer 4 is 60 nm to 100 nm, low reflectance isobtained over all wavelength ranges. In particular, if the layerthickness is 80 nm or less, the reflectance of light within the range of450 nm to 500 nm, which is greatly affected by the light incident fromthe exterior, is reduced.

[0124] In this embodiment, the second low reflection layer 4 iscrystallized at a high temperature by the sputtering method to have anuneven surface. The surface of the second low reflection layer 4 isdeposited, for example, such that the arithmetic mean roughness Rameasured by a stylus-type step-difference measuring apparatus is 4 nm to11 nm. Further, the substrate 1 and the second low reflection layer 4are crystallized such that their arithmetic mean roughness Ra is 10 nmto 100 nm. As such, it is possible to reduce the reflectance much more.In order for the first low reflection layer 3 and the second lowreflection layer 4 to be left at the desired portions, a photosensitiveresin is applied and is then patterned by the photolithography method.The second low reflection layer 4 (ITO) is etched by aqua regia usingthe photosensitive resin as a mask. Also, the first low reflection layer3 (Ti) is etched by a buffer hydrofluoric acid (BHF) solution in whichthe ratio of hydrofluoric acid to fluoric ammonium is 1:6. Herein, thefirst low reflection layer 3 and the second low reflection layer 4 areleft at a region wider than a region on which the respective EL layers 5are deposited. That is, the low reflection layers are extended to thelower region on which the bank 7 is formed, and the spacing (gap)between the first and second low reflection layers 3 and 4 is formed asnarrow as possible. In this way, it can suppress a reduction invisibility due to the reflection of light from a layer closer to thesubstrate than the first low reflection layer and a rear side of thesubstrate. Recently, when the patterning is performed by thephotolithography method, the minimum value of the gap is almost equal tothe thickness of the layer to be processed. For example, if the totalthickness of the first low reflection layer 3 and the second lowreflection layer 4 is 0.1 μm, the minimum value of the gap is almost 0.1μm. Herein, the first low reflection layer 3 and the second lowreflection layer 4 may be formed in only desired portions by, forexample, a mask deposition method. A mask deposition is a method offorming a pattern by performing the vacuum deposition in a state where amask, which is made of, for example, stainless steel having a thicknessof 40 μm to 100 μm and in which openings are formed at the desiredportions, adheres closely to the substrate. Further, chromium (Cr; 4.5eV of work function) may be deposited on the second low reflection layer4.

[0125] Next, a film composed of an inorganic material is formed on asurface of the planarizing insulating film 52 by a PECVD method, etc.,and is patterned to leave a region in which the bank 7 is formed and acircumferential region of the second low reflection layer 4, therebyforming an insulating passivation film 61. The insulating passivationfilm 61 is formed to have a thickness of 0.2 μm to 1.0 μm, for example,if the light-emitting layer 5 is formed to have a thickness of 0.05 μmto 0.2 μm.

[0126] Then, the bank 7 of an organic material is formed along thescanning line ‘gate’ and the data line ‘sig’. When the deposition isperformed by a liquid drop discharging method, the bank 7 functions toprevent a liquid material containing an organic compound fromoverflowing to adjacent regions. Accordingly, for example, if thelight-emitting layer 5 is formed of a thickness of 0.05 μm to 0.2 μm,the bank is formed of a height of 1 μm to 2 μm. The formation of thebank may be performed by, for example, a photolithography method, aprinting method, and other methods.

[0127] A solution containing a polymer organic compound is discharged inthe region defined by the bank 7 using the liquid drop discharging(inkjet) method to form the EL layer 5 (the hole injecting andtransporting layer 5A and the light-emitting layer 5B). In the EL layer5, the discharging and drying of a liquid material containing an organiccompound are repeatedly performed on every layer. As a specific exampleof the light-emitting layer 5B, a material for a red light-emittinglayer includes a solution, in which an inky PPV precursor is doped withpigment, such as rhodamine, beryllium, and the like, or an inky PPVprecursor (MHE-PPV). A material for a blue light-emitting layer includesan inky solution in which a polyfluorene derivative is dissolved by anaromatic solvent such as xylene. Next, in the case of the PPV precursorsolution (PPV precursor solution is diluted by DMF and is. convertedinto ink), a solvent is removed from the PPV precursor under reducedpressure, and the solution is conjugated and settled by heat treatmentat 150° C. Alternatively, in the case of a material commonly usable forthe respective pixels, each layer of the EL layer 5 may be deposited bya spin coating method, a deep method, and the like. Also, in a casewhere organic EL elements of the EL layer 5 are composed of a lowmolecular organic compound, the region on which the EL layer 5 isdeposited remains, and other regions are masked. Then, the region may bedeposited with organic compounds for the respective layers.Alternatively, in order to improve the efficiency of electron injectionfrom the conductive film 6, an electron injecting layer composed of, forexample, magnesium/silver (Mg/Ag) may be deposited by a depositionmethod. If the EL layer 5 is formed, the conductive film 6 of ITO isdeposited on the entire surface of at least the display portion by thedeposition method.

[0128] Herein, when the first low reflection layer 3 is made of titanium(comprises titanium oxide), the hole injecting and transporting layer5A, the light-emitting layer 5B (LEP), and the conductive film 6 (ITO)are preferably formed of the thickness as shown in Table 1 in order toreduce reflectance. TABLE 1 Light- Second Conductive emitting Holeinjecting reflection film 6 layer 5B and transporting layer 4 (ITO)(LEP) layer 5A (PEDOT) (ITO) (1) 145 ± 10  80 ± 10  90 ± 10 72 ± 10 (2)145 ± 10 160 ± 10  90 ± 10 72 ± 10 (3) 145 ± 10  80 ± 10 180 ± 10 72 ±10 (4) 145 ± 10 160 ± 10 180 ± 10 72 ± 10

[0129] On the conductive film 6, a thin sealing film 8 composed of atransparent resin is formed on the entire display panel. Therefore, theEL layer 5 (an organic EL element) does not vary in property when it isexposed to moisture and air, and thus its lifespan is lengthened. Thesealing film 8 is obtained by depositing, for example, SiON(silicon-oxynitride) or MgO (magnesium oxide) to a film thicknesscapable of transmitting a visible ray using a deposition method and byadhering a polymer film, such as polyvinyl fluoride thereto by adhesiveor by melting and attaching it thereto by heat. Also, the displayportion may be covered with a transparent substrate, which will bedescribed later.

[0130]FIG. 6 is a graph depicting the relationship between reflectanceand a light incident/emitting angle for every wavelength when the firstlow reflection layer 3 and the second low reflection layer 4 aredeposited. In FIG. 6(a), titanium for forming the first low reflectionlayer 3 is sputtered, and ITO for forming the second low reflectionlayer 4 is sputtered of a thickness of 78 nm at room temperature (RT).In FIG. 6(b), after the sputtering method is performed under the sameconditions as the above, the layers are treated in an atmosphere at atemperature of 280° C. during one hour. In FIG. 6(c), only pure titaniumis sputtered for forming the first low reflection layer 3. And, in FIG.6(d), three layers of Al, ITO, and Al are formed. In FIG. 6(d), theconditions, such as the layer thickness of ITO, are the same as thoseshown in FIG. 6(a). Therefore, there is a possibility that the maximumreflectance will not be obtained under the conditions shown in FIG.6(d), but it is shown for reference.

[0131]FIG. 7 is a graph depicting the relationship between reflectanceand a light incident/emitting angle for every wavelength when the firstlow reflection layer 3 is formed of Ti and the second low reflectionlayer 4 is formed of ICO. In FIG. 7(a), ICO for forming the second lowreflection layer 4 is formed of a thickness of 38 nm, and in FIG. 7(b),ICO for the second low reflection layer 4 is formed of a thickness of 76nm. ICO is deposited by the sputtering method using an indium ceriumoxide containing 20 at % (the ratio of the number of atoms (molecules))of a cerium oxide as a target. Although a layer capable of reducingreflectance and a light incident/emitting angle vary in accordance withthickness, it will be understood that all of the cases reduces thereflectance of light with a wavelength of approximately 500 nm in whichvisibility is high. Further, according to FIGS. 6 and 7, it isunderstood that reflectance is low when the first low reflection layer 3is made of Ti.

[0132] According to the first embodiment described above, thereflectance can be effectively reduced by the interaction of the firstlow reflection layer 3, the second low reflection layer 4, the EL layer5, and their interfaces. Therefore, the visibility of images displayedon the display panel can be improved outdoors. In particular, whenorganic EL elements, which are self-luminescent elements, are used for adisplay panel (display device), such an effect is obtained. Further, Ti,TiN or TiW is used for the first low reflection layer 3, and ITO is usedfor the second low reflection layer 4, thereby effectively suppressingreflection. In addition, a basic low reflection structure is composed oftwo layers of the first low reflection layer 3 and the second lowreflection layer 4, thereby easily manufacturing the display panel.

Second Embodiment

[0133]FIG. 8 is a cross-sectional view showing a part of the displaypanel according to a second embodiment of the present invention.Elements indicated by the same reference numerals as those in FIG. 1correspond to those described in the first embodiment, and thus thedescription thereof will be omitted herein. Although FIG. 8 shows only apart that is required for the description of this embodiment, thestructure of this embodiment is not different from that of the firstembodiment. Reference numeral 11 indicates a black layer (combining theaforementioned planarizing insulating film 52) into which an insulatingphotosensitive resin containing a black pigment is solidified. Further,reference numeral 5A indicates a hole injecting and transporting layer,and reference numeral 5B indicates a light-emitting layer, which areparts of the EL layer 5. In addition, ITO used for the second lowreflection layer 4 may be used for the hole injecting and transportinglayer 5A.

[0134] In this embodiment, the black layer 11 absorbs the light incidentfrom the exterior to suppress the reflection of light and thus reducereflectance. In this embodiment, since the black layer 11 is depositedby a spin coating method, the influence of the step difference due to adriving element, wiring lines, etc., upon the reflectance can bereduced.

[0135] Next, a method of manufacturing the display panel according tothe present embodiment will be described. A process of forming the TFT30 and the electrode 2 on the substrate 1 is substantially equal to thatof the first embodiment, and the description thereof will be omittedherein. The substrate is rotated at a predetermined speed of revolution,and an insulating photosensitive resin containing a black pigment isdropped on the substrate. In addition, the substrate is rotated at agiven speed of revolution during a given period of time to perform aspin coating. For example, COLOR MOSAIC CK CK-A029 (trademark), which iscommercially available from FUJIFILM Arch Co., Ltd., is used as thephotosensitive resin. This photosensitive resin has an OD value of 3(value indicated by -log (reflectance or transmittance)) in the case ofa thickness of 1 μm. The number of revolutions, time, and the amount ofresin are adjusted such that the layer thickness is about 1 μm (forexample, the number of revolutions after dropping is 1000 rpm, time is30 seconds, and the amount of resin dropped on the substrate of 4 inchesis 2 ml). After that, a prebake is performed at 110° C. during 120seconds. After the resin is exposed (for example, radiate ultravioletrays of 400 mJ/cm²) to form a pattern of the electrode 2 (hole injectinglayer 5A), the substrate is dipped in a 20% solution (26° C.) of adeveloper CD (trademark), which is commercially available from FUJIFILMArch Co., Ltd., during 45 seconds and is then developed, washed inwater, and dried (220° C., 60 minutes). FIG. 9 is a photomicrograph ofthe black layer 11 patterned on the substrate 1, which is magnified 100times. Although the black layer has grooves, the black layer ispreferably patterned such that through-holes are formed at the positionscorresponding to the pixels in order to obtain the maximum effect. Theconnection between the hole injecting and transporting layer 5A and theelectrode 2 is obtained by performing such patterning.

[0136] In the case of forming the EL layer 5 using a polymer organiccompound, after the bank 7 is formed similarly to the first embodiment,a liquid material containing the polymer organic compound, which is usedfor forming the hole injecting and transporting layer 5A, is dischargedby a liquid drop discharging method and is then solidified to form thehole injecting and transporting layer 5A. Further, a liquid materialcontaining the polymer organic compound, which is used for forming thelight-emitting layer 5B, is discharged by the liquid drop dischargingmethod and is then solidified to form the EL layer 5.

[0137]FIG. 10 is a graph depicting the relationship between reflectanceand a light incident/emitting angle of the black layer 11. After the ELlayer 5 is formed, the conductive film 6 and the sealing film 8 isformed by the same method as that used in the first embodiment. Theblack layer 11 of the display panel formed by the above method has thewavelength dependency on reflectance in a visible ray range as shown inFIG. 10.

[0138] As described above, according to the second embodiment, the blacklayer 11 absorbs the light incident from the exterior to suppress thereflection of light and thus reduces reflectance. Further, since theblack layer 11 is formed by a spin coating method, the influence of thestep difference due to a driving element, wiring lines, etc., uponreflectance can be reduced, and the uniformity of the film thickness ofthe EL layer 5 can be improved, thereby improving the uniformity in thelight-emitting surface.

Third Embodiment

[0139]FIG. 11 is a cross-sectional view showing a part of the displaypanel according to a third embodiment of the present invention. Elementsindicated by the same reference numerals as those in FIG. 8 are the sameor equivalent as those described in the first and second embodiments,and thus the description thereof will be omitted herein. Referencenumeral 11A indicates a black layer formed of an allotrope of carbonhaving conductivity.

[0140] In the present embodiment, the black layer 11A absorbs the lightincident from the exterior to decrease the reflecting light and thusreduces reflectance, as similar to the second embodiment. In thisembodiment, the black layer 11A is formed of an allotrope of carbon.Since the black layer 11A is made of carbon having conductivity, it isnot necessary to electrically connect the electrode 2 to the holeinjecting and transporting layer 5A directly.

[0141] Next, a method of manufacturing the display panel according tothe present embodiment will be described. A process of forming the TFT30 and the electrode 2 on the substrate 1 is substantially equal to thatof the first embodiment, and the description thereof will be omittedherein. The black layer 11A is formed of carbon. Herein, DLC (DiamondLike Carbon) is used for forming the black layer 11A. DLC is the generalterm for a carbon thin film deposited by a vapor phase growth methodusing ions, and the carbon thin film has high hardness and thetransparency of infrared rays similar to those of diamond. DLC isdeposited by, for example, a sputtering method, CVD, etc. As such, athinner layer may be formed and the influence on light-emitting elementsmay be reduced, compared with performing a spin coating method as in thesecond embodiment.

[0142]FIG. 12 is a graph depicting the relationship between reflectanceand a light incident/emitting angle of the black layer 11A. A method offorming the bank 7, the EL layer 5, the conductive film 6, and thesealing film 8 is equal to that of the first and second embodiments, andthus the description thereof will be omitted. However, the black layer11A may be deposited after the bank 7 is first formed.

[0143] In addition, the black layer 11A is formed of DLC, but may beformed of, for example, an allotrope of carbon, such as amorphouscarbon, graphite, and the like. Graphite is deposited by a vacuumdeposition method or a sputtering method. In the case of using thesputtering method, provided that carbon atom can be sputtered, it ispreferable to utilize a target made of any allotrope.

[0144] According to the third embodiment, since the black layer 11A isformed of an allotrope of carbon having conductivity by the sputteringmethod or the vacuum deposition method, a thinner black layer isobtained, thereby reducing the influence of light-emitting elements upontheir characteristics.

Fourth Embodiment

[0145] According to the second and third embodiments, the light incidentfrom the exterior is absorbed by the black layer 11 or 11A to suppressreflection. The absorbed light is converted into heat. Therefore, thetemperature of the display panel increases, and the heat has aninfluence on the light-emitting lifespan of an organic compound formingthe EL layer 5. In order to prevent the above problem, an element havinga Peltier effect (hereinafter, referred to as ‘Peltier element’) isprovided. The Peltier effect means an endothermic and exothermicphenomenon by current. If DC current is applied to a junction portion ofa p-type semiconductor and an n-type semiconductor, anendothermic/exothermic reaction is generated in the junction portion.The Peltier element cools down a device using such a reaction.Therefore, it is possible to precisely control the temperature by onlycontrolling a driving current.

[0146]FIG. 13 shows a display panel provided with a Peltier element. ThePeltier element comprises a metallic electrode 100, an N-typesemiconductor layer 103, a P-type semiconductor layer 104, and aradiating electrode 105. Next, a method of manufacturing the Peltierelement will be described. First, for example, a silicon oxide film isdeposited on a substrate 1 as a passivation film (not shown). And, metalfor the metallic electrode 100 is deposited thereon, for example, with athickness of 200 nm by a sputtering method. For example, chromium (Cr)is used as the material for forming the metallic electrode 100. Andthen, the substrate is patterned by a photolithography method to formthe metallic electrode 100 in a desired shape.

[0147] Further, a silicon oxide film for the insulating film 101 isdeposited on the desired portions of the metallic electrode 100 by a CVDmethod, etc. Then, a driving element is formed thereon by the samemethod as in the first embodiment. It is preferable to manufacture thelight-emitting device after manufacturing the Peltier element because ofthe influence on the light-emitting layer 5.

[0148] After the insulating film 101 is patterned by a photolithographymethod, the desired portions of the insulating film 101 are etched, andthe N-type semiconductor layer 103 and the P-type semiconductor layer104 are deposited. At this time, for example, BiTe (bismuth telluride)doped with selenium (Se) is used for forming the N-type semiconductorlayer 103. Further, BiTe doped with antimony (Sb) is used for formingthe P-type semiconductor layer 104. The above materials are depositedwith a thickness of 500 nm by, for example, the sputtering method,respectively. Then, after aluminum (Al) for forming the radiatingelectrode 105 is deposited with a thickness of 500 nm and is patternedby the photolithography method, the aluminum is etched such that thedesired portions remain. After that, the substrate is maintained at 150°C. (firing temperature of BiTe) during 1 hour to form the N-type.semiconductor layer 103, the P-type semiconductor layer 104, and theradiating electrode 105, thereby manufacturing a Peltier element. TheN-type semiconductor layer 103 and the P-type semiconductor layer 104may be formed by doping the semiconductor layer, which is an activeregion of the driving element, with a high concentration of N-typeimpurity and P-type impurity, respectively. Further, the radiatingelectrode 105 may be formed using the same layer as the wiring linelayer of the driving element.

[0149] As described above, according to the fourth embodiment, since theheat converted from the light absorbed by the black layer 11 or 11A isradiated externally by the Peltier element, the lifespan of an organicEL element, which is easily affected by the temperature, can belengthened. In addition, the Peltier element is formed together with theTFT 30, thereby effectively arranging the circuit (element).

Fifth Embodiment

[0150] Although not described specifically in the above second and thirdembodiments, after the second low reflection layer 4 described in thefirst embodiment is deposited on the black layer 11 or 11A, the EL layer5 may be deposited thereon.

Sixth Embodiment

[0151]FIG. 14 shows a sealing method according to a sixth embodiment ofthe present invention. In this embodiment, a sealing method used insteadof the sealing film 8 according to the first embodiment will now bedescribed. In FIG. 14(a), for example, a frame portion of the periphery(if necessary, comprising a display control circuit) of the displayportion adheres to a transparent substrate 8A, such as a glasssubstrate, having a concave portion using an adhesive, etc., and is thensealed. At that time, the sealing process is performed under vacuum toprevent moisture from coming thereinto. Further, a desiccant forabsorbing the moisture permeated through the adhesive may be filledtherein. When the second low reflection layer 4 is deposited, an ITOlayer may be deposited on the frame portion such that the adhesive iseasily absorbed thereto due to the roughness effect, thereby increasingits adhesion. In this way, the permeation of moisture or oxygen can besecurely prevented. In FIG. 14(b), a space between the transparentsubstrate 8A and the conductive film 6 is filled with an adhesive 12,and then they adhere to each other. The adhesive 12 prevents moisturefrom permeating into the organic EL element.

[0152] As described above, according to the sixth embodiment, instead ofthe sealing film 8, the transparent substrate 8A having the concaveportion is adhered and sealed, or an adhesive is filled in the concaveportion of the transparent substrate 8A. Therefore, it is possible toprevent moisture from permeating into the organic EL element 5, therebyprolonging the light-emitting lifespan of the organic EL layer 5.

Seventh Embodiment

[0153] In the aforementioned embodiments, an active matrix display panelis described. However, the present invention is not limited thereto, andmay be applied to a passive matrix display panel.

Eighth Embodiment

[0154] In the aforementioned embodiments, a display panel utilizingorganic EL elements is described. However, the present invention is notlimited thereto, but may be applied to other display panels utilizingflat display panels, such as a display panel using inorganic ELelements, LCD, and PDP. Furthermore, in the aforementioned embodiments,a display panel of the so-called top emission structure in which alight-emitting light of the light-emitting layer 5B is emitted from thelight-emitting element forming surface on the substrate 1 is described.However, the present invention is not limited thereto, but may beapplied to the so-called bottom emission structure in which alight-emitting light of the light-emitting layer 5B is emitted from asurface opposite to the light-emitting element forming surface on thesubstrate 1. Further, when the light-emitting surface is covered withglass, which has the reflectance of 4%, an antireflection (AR) processmay be performed thereon, that is, a multi-layered antireflection filmobtained by depositing a coating material may be formed on the glass, oran antireflection film may adhere to the glass.

Ninth Embodiment

[0155]FIG. 15 is a view depicting electronic apparatuses according to aninth embodiment of the present invention. FIG. 15(a) shows a PDA(personal digital assistant), FIG. 15(b) shows a cellular phone, andFIG. 15(c) shows a digital camera. Although it is not shown in thepresent embodiment, a display panel of the present invention may beapplied to electronic apparatuses having a displaying function andutilizing a display panel, such as personal computers and electronicgame consoles. In particular, when a display panel of the presentinvention is applied to electronic apparatuses used outdoors, it canhave a marvelous effect.

1. A display panel comprising: a first low reflection layer made oftitanium and deposited on a substrate; a second low reflection layermade of indium tin oxide and deposited on the first low reflectionlayer; and light-emitting elements deposited on the second lowreflection layer.
 2. A display panel comprising: a substrate providedwith control elements for controlling the supply of electric charge topixels; a first low reflection layer made of titanium and deposited atpositions corresponding to the pixels on the substrate; a second lowreflection layer made of indium tin oxide and deposited on the first lowreflection layer; and light-emitting elements, functioning as thepixels, deposited on the second low reflection layer.
 3. A display panelcomprising: a substrate provided with control elements for controllingthe supply of electric charge to pixels; a first low reflection layermade of titanium and deposited at positions corresponding to the pixelson the substrate; a second low reflection layer made of indium tin oxideand deposited on the first low reflection layer; light-emittingelements, as functioning the pixels, deposited on the second lowreflection layer and emitting light based on the electric chargesupplied under the control of the control elements; a conductive filmdeposited on the light-emitting elements and supplying to thelight-emitting elements electric charge having a polarity opposite tothe electric charge supplied from the second low reflection layer; and asealing member provided on the conductive film as a display surface andfacing the substrate.
 4. A display panel according to any one of claims1 to 3, wherein the second low reflection layer is deposited with athickness of 60 nm to 100 nm.
 5. A display panel according to any one ofclaims 1 to 3, wherein the second low reflection layer is made of indiumzinc oxide, gallium zinc oxide, or indium cerium oxide instead of indiumtin oxide.
 6. A display panel according to claim 3, wherein theconductive film is made of indium cerium oxide.
 7. A display panelaccording to any one of claims 1 to 3, wherein the second low reflectionlayer is deposited such that the arithmetic mean roughness Ra of surfacethereof measured by a stylus-type step-difference measuring apparatus isin the range of 4 nm to 11 nm.
 8. A display panel according to any oneof claims 1 to 3, wherein the first low reflection layer is made oftitanium nitride instead of titanium.
 9. A display panel according toany one of claims 1 to 3, wherein the first low reflection layer is madeof an alloy of titanium and tungsten instead of titanium.
 10. A displaypanel according to any one of claims 1 to 3, wherein a titanium oxidelayer is provided at least between the first and second low reflectionlayers.
 11. A display panel according to any one of claims 1 to 3,wherein the first low reflection layer is deposited with a thickness of30 nm to 400 nm.
 12. A display panel according to claim 3, wherein ITOfor forming the second low reflection layer is deposited with athickness of 62 nm to 82 nm, ITO for forming the conductive film isdeposited with a thickness of 135 nm to 155 nm, a light-emitting polymerfor forming the light-emitting layer constituting the light-emittingelement is deposited with a thickness of 70 nm to 90 nm or 150 nm to 170nm, and a hole injecting and transporting layer is deposited with athickness of 80 nm to 100 nm or 170 nm to 190 nm.
 13. A display panelaccording to claim 2 or 3, wherein a planarizing film is providedbetween the substrate and the first low reflection layer.
 14. A displaypanel according to any one of claims 1 to 3, wherein a chromium layer isfurther deposited on the second low reflection layer.
 15. A displaypanel according to claim 2 or 3, wherein in a step of forming thecontrol elements and the wiring lines and a step of forming the firstlow reflection layer or the second low reflection layer, some of or allof the steps are commonly used.
 16. A display panel comprising a blacklayer having a function of reducing a step difference at a lower portionand light-emitting elements provided on the black layer.
 17. A displaypanel comprising a conductive black layer formed on a substrate andlight-emitting elements provided on the black layer.
 18. A display panelaccording to claim 17, wherein the black layer is made of an allotropeof carbon.
 19. A display panel according to any one of claims 16 to 18,wherein control elements for controlling the supply of electric chargeto the light-emitting elements are formed on the substrate, and Peltierelements are formed at portions other than a display portion on thesubstrate.
 20. An electronic apparatus comprising the display panelaccording to any one of claims 1 to 19 to perform display.
 21. A methodof manufacturing a display panel having a plurality of pixels,comprising the steps of: forming a first low reflection layer made oftitanium at positions corresponding to the pixels on a substrate; andforming a second low reflection layer made of indium tin oxide on thefirst low reflection layer.
 22. A method of manufacturing a displaypanel according to claim 21, wherein after the first and second lowreflection layers are deposited by either a sputtering method or adeposition method, the first low reflection layer and the second lowreflection layer are patterned so as to remain only at the positionscorresponding to the pixels.
 23. A method of manufacturing a displaypanel according to claim 21, wherein after masking is previouslyperformed at the positions corresponding to the pixels, the first lowreflection layer and the second low reflection layer are deposited byeither the sputtering method or the deposition method so as to remainonly at the positions corresponding to the pixels.
 24. A method ofmanufacturing a display panel according to any one of claims 21 to 23,the method further comprising the steps of: forming light-emittingelements at the positions corresponding to the pixels after forming thesecond low reflection layer; forming, on the light-emitting elements, aconductive film for supplying to the light-emitting elements electriccharge having a polarity opposite to the electric charge supplied fromthe second low reflection layer; and performing sealing using a sealingmember.
 25. A method of manufacturing a display panel, comprising thesteps of: forming control elements for carrying out display control onpixels on a substrate; applying a photosensitive resin containing ablack pigment on the control-element-forming surface of the substrate toform a black layer; and forming through-holes or grooves for supplyingelectric charge at the positions corresponding to the pixels using theblack layer.
 26. A method of manufacturing a display panel, comprisingthe steps of: forming control elements for carrying out display controlon pixels on a substrate; and forming a conductive black layer atpositions corresponding to the pixels on the control-element-formingsurface of the substrate.
 27. A method of manufacturing a display panelaccording to claim 24 or 25, wherein active regions of the controlelements are made of silicon, and when the control elements are formed,Peltier elements are formed at portions other than a display portion onthe substrate.
 28. A method of manufacturing a display panel accordingto claim 27, wherein in the step of forming the black layer, the blacklayer is formed of graphite deposited by a vacuum deposition method or asputtering method.
 29. A method of manufacturing a display panelaccording to claim 27, wherein in the step of forming the black layer,the black layer is formed of diamond like carbon deposited by a chemicalvapor deposition method.
 30. A method of manufacturing a display panelaccording to any one of claims 25 to 29, the method further comprisingthe steps of: forming light-emitting elements at the positionscorresponding to the pixels after forming the black layer; forming, onthe light-emitting elements, a conductive film for supplying to thelight-emitting elements electric charge having a polarity opposite tothe electric charge supplied from the black layer; and performingsealing using a sealing member.
 31. A method of manufacturing a displaypanel according to claim 24 or 27, wherein in the step of forming thelight-emitting elements, after banks are formed to store a solution of apolymer compound for the light-emitting elements at positions where thepixels are formed, the solution is discharged at the positions where thepixels are formed by a liquid drop discharging method.